Method of bonding wafers
AssigneeAnalog Devices, Inc.
InventorsThomas Kieran Nunan, Changhan Yun, Christine H. Tsau
Life of this patent
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Abstract
A method of bonding wafers with an aluminum-germanium bond includes forming an aluminum layer on a first wafer, and a germanium layer on a second wafer, and implanting the germanium layer with non-germanium atoms prior to forming a eutectic bond at the aluminum-germanium interface. The wafers are aligned to a desired orientation and the two layers are held in contact with one another. The aluminum-germanium interface is heated to a temperature that allows the interface of the layers to melt, thus forming a bond. A portions of the germanium layer may be removed from the second wafer to allow infrared radiation to pass through the second wafer to facilitate wafer alignment.
Claims20
A method of capping a wafer, the method comprising:
- providing a first wafer having a first face, the first face bearing an aluminum bonding layer;
- providing a cap wafer having a second face, the second face bearing an epitaxial germanium layer, the epitaxial germanium layer comprising an amorphous region in which the crystal structure of the germanium is disrupted by implanted ions;
- aligning the aluminum layer to the amorphous region;
- holding the aligned wafers together, at temperature in the range of about 400 degrees to about 500 degrees Celsius until an aluminum-germanium bond is formed at the interface of the aluminum layer and the amorphous region.
A wafer configured to bond to a second wafer, the wafer having a first surface, the wafer comprising:
- a germanium layer on the first surface, the germanium layer further comprising:
- a second surface parallel to, and facing away from, the first surface;
- and
- an amorphous region comprising ions, the amorphous region extending into the germanium layer from the second surface, wherein the amorphous region is configured to be exposed to the second wafer.
A capped die comprising:
- a die having a first face, and an aluminum layer on the first face;
- a cap having a crystalline orientation, and a second face;
- a germanium layer on the second face;
- wherein the germanium layer is parallel to the second face, and wherein the crystalline orientation of the germanium layer matches the crystalline orientation of the second face;
- an amorphous region within the germanium layer, the amorphous region comprising ions and extending into the germanium layer from the second face;
- and
- a bond region comprising a eutectic bond between the aluminum layer and germanium layer.
Dependencies are inferred from the claim text.